[Written by a veterinarian] Can cats get bitten by mosquitoes? The dangers of heartworm and safe insect repellent measures

Do you know about a disease called "heartworm disease"? If you own a dog, you might know that it's a parasitic disease transmitted by mosquitoes, but for cat owners, it might be an unfamiliar illness. It's known that heartworms, transmitted by mosquitoes, can infect not only dogs but also cats. This time, we will explain heartworm disease in cats.

Can cats get bitten by mosquitoes? Common biting spots and symptoms

Beware of thin-haired areas like ears, nose, and paw pads

Mosquitoes appear in the cooler mornings and evenings rather than during the hot daytime hours. They can also enter through gaps in screens, so even indoors, your cat can get bitten. Mosquitoes are attracted to carbon dioxide, body temperature, and body odor emitted by animals. Even in cats, whose entire bodies are covered in fur, areas with thin fur such as around the ears, the tip of the nose, and paw pads are at risk of mosquito bites.

Symptoms and first aid when bitten by a mosquito

Similar to humans, redness and intense itching will appear. Symptoms include the cat scratching the bitten area vigorously with its paws or shaking its head. Also, the bitten area may swell and become red.

If your cat is itchy, do not easily use human itch relief medications. Human itch relief medications may contain ingredients that are harmful to cats. If symptoms are severe, cool the area with water and visit a veterinarian.

[Veterinarian's Warning] The terrifying "feline heartworm disease" transmitted by mosquitoes

What is feline heartworm disease (Dirofilariasis)?

Heartworms (Dirofilaria immitis) are parasites transmitted by mosquitoes. They parasitize the heart and pulmonary arteries of dogs, but can also infect humans and cats. When a mosquito carrying heartworm larvae feeds, it introduces the larvae into the animal's body. At the time of entry, the larvae are about 1 mm long, but they grow to about 10-15 cm inside the body and parasitize the heart and pulmonary arteries. Since dogs are the natural host for heartworms, many larvae mature into adult worms, and in the heart, female worms produce microfilariae (baby worms) that circulate in the bloodstream. While dozens to hundreds of adult heartworms can parasitize a dog's heart, most larvae die in cats because cats are not the natural host for heartworms. Only about 1-3 worms typically reach the heart.

Hard-to-notice early symptoms and the risk of "sudden death"

Even if a cat is infected with heartworms, most show no symptoms or only temporary symptoms such as coughing. Feline heartworm disease is more difficult to diagnose than canine heartworm disease because the number of parasites is small, making detection difficult with test kits. It starts with symptoms such as coughing, vomiting, difficulty breathing (asthma-like symptoms), and loss of appetite. If it worsens, it can lead to ascites and pleural effusion, respiratory distress, and rarely, sudden death, making it a terrifying disease.

Why "indoor-only cats" are still at risk of infection

Mosquitoes can enter indoors even through gaps in screen doors. The idea that "my cat doesn't go outside, so it's fine" is a big misconception. Data shows that even indoor cats, if not given heartworm preventive medication, have an infection rate of about 10%.

Is human mosquito repellent harmful to cats? Dangers and precautions for essential oils and mosquito coils

Can common mosquito coils and one-push sprays be used?

The "pyrethroid" insecticides found in common mosquito coils and sprays are rapidly broken down in the bodies of mammals, including cats, so they can be used safely. However, if the chemical gets directly on the cat or if it's used in a closed room, symptoms such as vomiting, diarrhea, or drooling may occur, so ventilation and usage methods must be carefully considered.

[Strictly Prohibited] Why essential oils and herbal mosquito repellents are dangerous for cats

Essential oils (e.g., peppermint oil, tea tree oil) commonly used in human organic insect repellent sprays are highly toxic to cats. Cats lack the "glucuronidation" metabolic function in their liver that breaks down fat-soluble compounds, so they cannot excrete toxic fat-soluble substances from their bodies, leading to serious poisoning symptoms. Therefore, do not use essential oils or herbs.

[Safety Measures] Protecting your beloved cat from mosquitoes! Necessary prevention even for indoor cats

The most reliable prevention is "heartworm preventive medication" from a veterinarian.

Since it's impossible to completely prevent mosquito bites, administering preventive medication once a month (spot-on type or oral medication) is the most important and safest measure. Heartworm preventive medication kills heartworm larvae that have entered the body. We are often asked in the examination room, "Is this a medication that prevents mosquito bites?" but it does not repel mosquitoes themselves. It can prevent heartworm disease by regular monthly use during the mosquito season (May to November). However, the effect of the medication wears off in about a month, so if it's not administered regularly, the preventive effect will decrease.

Physical mosquito intrusion prevention measures you can take at home

While it's impossible to completely prevent mosquito intrusion, taking measures can reduce it. Repair torn screens, quickly enter and exit the front door, eliminate standing water (such as planter saucers) where mosquitoes lay eggs to cut off their breeding grounds, and generally improve your environment.

Summary: Protect your cat from the threat of mosquitoes by having correct knowledge and thoroughly using preventive medication.

Feline heartworm disease is not a well-known illness, but it is thought that it may become more prevalent in the future due to global warming. Even a small number of heartworms can lead to sudden death in cats. Since it can be prevented by regularly administering heartworm preventive medication, ensure regular administration of these medications.

Using essential oils or herbs to repel mosquitoes can be harmful to cats. First, eliminate mosquito entry points by improving your environment, and create an environment where both humans and cats can get through summer without being bothered by mosquitoes.

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